1. Field of the Invention
This invention relates to a closed, patient access system which automatically reseals after administering medication using a standard medical implement that directly connects with the system without the need of any intermediary needles, caps or adaptors. A two-way valve eliminating dead space is used which includes a seal which, upon being compressed by the medical implement, is pierced to open the valve and reseals upon being decompressed, maintaining a fluid tight seal even at high pressures and after repeated uses.
2. Background Discussion
The manipulation of fluids for parenteral administration in hospital and medical settings routinely involves the use of connectors and adaptors for facilitating the movement of fluids between two points. Most fluid connectors and adaptors employ needles to pierce a septum covering sterile tubing or to pierce the septum of a medicament container of fluid. Fluid then passes from the container or fluid filled tubing into a syringe or second set of tubing. These connectors and adaptors often have mechanical or moving parts. Since the ready passage of fluids through the connectors and adaptors is often critical to patient survival, it is imperative that the connectors and adaptors function reliably and repeatedly. Adaptors and connectors that malfunction during use may be life-threatening. The more mechanical or moving parts such as springs and diaphragms, the more likely that they will function improperly. Improper functioning can result in the introduction of air embolisms into a patient. Thus, the fewer the mechanical parts, the more these connectors can be relied on and the better they will be accepted by the medical community.
Many connectors or valves, especially those employing several mechanical components, have a relatively high volume of fluid space within them. This xe2x80x9cdead spacexe2x80x9d within the device prevents the accurate introduction of precise fluid volumes and provides an opportunity for contamination upon disconnection of the device. Connectors and adaptors often include valves that permit or interrupt the flow of fluid along the course of fluid travel. Several of those commonly in use employ metal needles to puncture sterile seals. Such connectors are generally designed to accommodate fluid flow in one direction. This means that the fluid line must have connectors and tube aligned in complementary directions. These connectors often require further manipulation if, for example, the valve is inadvertently assembled in a direction that will not facilitate fluid flow. These manipulations increase handling, thereby increasing both the risk of contamination and the amount of time required to establish the fluid connection.
Metal needles employed as part of connector devices often have through-holes placed at the tip of the needle. Connection of the valve with a flow line involves piercing the needle through a sealed septum. Through-holes placed at the needle tip can core the septum and release free particulates into the flow line. Such an event can prove fatal to a patient. Such through-holes may also become clogged easily with material from the septum. Moreover, the use of a needle with a sharp point may also cause deterioration of the septum.
Reusable connectors and adaptors are preferred for medical applications since components must often be added or removed from a fluid line connected to a patient. Reusable connectors, however, are difficult to keep sterile. Sometimes caps are employed to cover the connector to keep it sterile. Frequently, these caps are lost, or simply not used because they are not readily available when needed.
A closed, patient access system that is easy to use and employs only a valve device in communication with the patient that need not be capped or interconnected with the medical implement through a needle or adaptor, is swabbable, is sufficiently durable to maintain its function after several manipulations, and maintains a fluid-tight seal at high pressures, would be of great benefit to the medical community.
The valve of this invention has several features, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this invention as expressed by the claims which follow, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled, xe2x80x9cDetailed Description of the Preferred Embodiments,xe2x80x9d one will understand how the features of this invention provide its advantages, which include safety, reliable and repeatable performance, simplicity of manufacture and use, and provides long life without malfunction.
A preferred embodiment of a seal used in the present invention comprises a series of O-ring elements stacked together and connected to form a unitary structure. The O-ring elements have increasing diameters, with the smallest diameter element being adjacent the proximal end of the cavity. The O-ring element closest to the proximal end of the seal contacts the wall of the spike proximal the through-holes when the seal is in a decompressed state, thereby preventing fluid from leaking from the interior of the spike through the proximal opening in the housing. It is desirable that at least the next immediate O-ring element also be in contact with the spike proximate the through-holes. Such a design prevents fluid from applying enough pressure on the slit to force the slit open while the seal is in the decompressed state. With the preferred embodiment fluid may reside in the spike and between the spike and the seal distal the through-holes without opening the slit in the seal cap. The seal is designed so that if this fluid pushes the seal upwards slightly, lifting the first and second O-ring elements upwards and off the spike, the O-ring elements immediately distal the first and second elements move up and contact the spike so as to ensure that fluid does not flow through the seal cap and out of the valve. Maintaining this contact around the spike avoids having fluid pressure on the slit force the slit open, permitting the valve to leak.
In another feature of the present invention, the housing is provided with fluid escape space, such as a groove or channel, to permit fluid contained between the exterior of the seal and the housing to escape during compression of the seal. In one embodiment, the proximal end of the housing is provided with at least one groove extending from the proximal end of the housing to indentations contained within the housing. During the compression of the seal, fluid between the exterior of the seal and the housing travels in a proximal direction through the grooves and out of the valve through the proximal end of the housing. In another embodiment, a channel is provided as the fluid escape space through the side wall of the housing. As the seal is compressed, fluid between the exterior of the seal and the housing travels through the channel to the exterior of the valve. As discussed in greater detail below, providing a groove or channel to permit fluid between the exterior of the seal and the housing side wall to escape from the valve during compression of the seal, provides several advantages.